Software Tools for Designing a SIMATIC PCS 7 DCS Plan: Lifecycle, Electrical, and Sizing Software

Designing a complete SIMATIC PCS 7 DCS plan spans multiple engineering domains and software tools: Siemens COMOS and Plant Automation Accelerator (PAA) provide integrated plant lifecycle and bidirectional P&ID/CFC synchronization; EPLAN Electric P8 handles electrical cabinet layouts and loop schematics; and the Siemens TIA Selection Tool / CDT size hardware controllers, I/O distribution, power budgets, and equipment schedules.

DCS Design Lifecycle and Multidisciplinary Engineering Phases

Designing a Distributed Control System (DCS) plan for an industrial processing facility (such as a pulp and paper mill, chemical plant, refinery, or pharmaceutical facility) is not a single drawing exercise. It encompasses four interdependent engineering disciplines:
1. Process & Instrumentation (P&ID) / Technological Planning: Defining process flow diagrams, instrument tag identifiers, pipe specifications, and control loops.
2. Electrical & Control Hardware Engineering: Cabinet panel layouts, 24V DC power distribution budgets, terminal strip wiring, I/O module channel allocations, and loop termination schematics.
3. Automation System Hardware & Topology Sizing: Sizing controllers (e.g. CPU 410-5H), distributed I/O racks (ET 200SP HA, ET 200M), communication processors, fiber optic network rings, and server/client station quotas.
4. Software Architecture & Control Strategy: Continuous Function Charts (CFC), Sequential Function Charts (SFC), safety matrices, and SCADA mimic displays.

Because no single application covers process chemistry, high-voltage panel wiring, and automation database compiling, industry engineers deploy a coordinated suite of specialized software tools.

Integrated Plant Engineering with Siemens COMOS and PAA

For holistic plant lifecycle engineering, Siemens provides the COMOS platform and SIMATIC PCS 7 Plant Automation Accelerator (PAA):

Siemens COMOS (Feed, P&ID, Automation):
COMOS serves as a centralized relational database platform where process engineers design P&IDs, electrical engineers design terminal diagrams, and automation engineers generate instrument schedules.
All objects (pumps, valves, transmitters) exist once in the global database. Changing an instrument range on a P&ID updates the instrument list and electrical cabinet drawing automatically.
SIMATIC PCS 7 Plant Automation Accelerator (PAA):
PAA is the direct bridge between plant design and PCS 7 engineering.
It provides bidirectional data exchange: signal lists, hardware configurations, and technological function blocks designed in PAA can be exported directly into SIMATIC Manager to generate HW Config, CFC charts, and WinCC tags automatically without manual data re-entry.
Changes made in PCS 7 during site commissioning can be synchronized back into PAA to preserve as-built plant documentation.

Electrical Cabinet, Loop Schematics, and CAD Tools

For physical enclosure design, cabinet thermal calculations, and electrical schematics:

EPLAN Electric P8 & EPLAN Pro Panel:
The global industry standard for detailed electrical engineering.
Used to generate multi-line schematics, 24V DC loop power distribution, terminal connection diagrams, cabinet door cutouts, and 3D cabinet layouts.
Interfaces directly with Siemens hardware catalog data (EPLAN Data Portal), importing exact 3D models and terminal pin definitions for S7-400, CPU 410-5H, and ET 200 distributed I/O.
Siemens Rittal Therm / Cabinet Thermal Tools:
Used alongside CAD software to calculate internal cabinet heat dissipation, sizing air conditioning units or heat exchangers to protect DCS hardware from thermal degradation.
AutoCAD / Microsoft Visio:
Ideal for conceptual engineering: high-level architectural block diagrams, network topology maps (Terminal Bus, Plant Bus, Fieldbus), control room layouts, and executive proposal presentations.

Hardware Sizing, Network Planning, and Bill of Quantities Tools

To size hardware, calculate power consumption, and formulate equipment schedules:

Siemens TIA Selection Tool (TST) / SIMATIC PCS 7 System Configurator:
Cloud-based and desktop planning tool provided by Siemens.
Allows engineers to drag and drop controllers (CPU 410-5H, S7-400H), distributed I/O racks, power supplies, and accessories.
Automatically calculates backplane power consumption, slot constraints, memory limits, and generates an exact equipment schedule with valid order numbers (MLFBs).
Legacy CDT (Configurator for Distributed Control Systems):
Classical DCS configuration utility historically used by Siemens engineering teams to generate system architectures and software license requirements.
SINETPLAN (Siemens Network Planner):
Used to design and simulate PROFINET and Industrial Ethernet networks.
Simulates network traffic loads, real-time IO data, and TCP/IP streaming (such as WinCC video or camera feeds) to guarantee deterministic bus performance before installing physical cables.

DCS Design Software Matrix across Project Lifecycle

Engineering DisciplinePrimary Software ToolsKey Outputs / DeliverablesPCS 7 Integration LevelProcess & Technological P&IDSiemens COMOS, SmartPlant P&ID, PAAP&IDs, Instrument Lists, I/O Data SheetsDirect bidirectional export to PCS 7 HW/CFCDCS System Hardware SizingSiemens TIA Selection Tool (TST), CDTEquipment schedule, Rack layouts, Power budgetsImports directly into STEP 7 HW ConfigElectrical Cabinet & LoopsEPLAN Electric P8, COMOS LogicalLoop sheets, Terminal diagrams, 3D Panel layoutEPLAN PLC export interface to STEP 7Industrial Network PlanningSiemens SINETPLAN, Microsoft VisioNetwork topology maps, Bus load simulationsVerification of PROFINET bandwidth limitsDCS Control ApplicationSIMATIC PCS 7 (STEP 7, CFC, SFC, WinCC)Executable PLC code, SCADA operator displaysNative runtime target platform

Verification

In Siemens TIA Selection Tool (TST), configure a redundant CPU 410-5H with 8 ET 200SP HA remote I/O nodes.
Confirm the tool validates slot capacity, power supply redundancy, and memory limits with zero errors.
Export the hardware configuration file (.aml / .xml).
In SIMATIC Manager, import the configuration into STEP 7 HW Config; confirm all racks, modules, and addresses populate cleanly without manual entry.
In COMOS / PAA, execute synchronization to verify tag and I/O cross-references match the physical hardware schedule.

Limitations and Operational Precautions

Planning Tool Results Disclaimer: Sizing tools such as the TIA Selection Tool or CDT provide planning aids and equipment estimates; they do not replace formal engineering peer reviews or manufacturer application engineering validation.
As-Built Synchronization Discipline: Failing to synchronize site commissioning modifications back into COMOS or EPLAN creates divergence between physical plant wiring and engineering schematics, complicating future plant expansions.
Procurement and Licensing Notice: When finalizing DCS hardware schedules and software packages, always validate exact order numbers (MLFBs), CPU System Expansion Card (SEC) Process Object capacities, and runtime licenses against the current Siemens ST PCS 7 catalog and obtain quotations from an authorized distributor.

Engineer FAQ

What is the difference between COMOS and PCS 7 Plant Automation Accelerator (PAA)?

COMOS is a comprehensive multi-discipline plant lifecycle platform (civil, piping, electrical, instrumentation). PAA is a specialized, streamlined edition focused specifically on control engineering and bidirectional PCS 7 data synchronization.

Can I design a complete DCS architecture using only Microsoft Visio?

Visio is effective for conceptual overview diagrams and network maps, but it lacks relational database intelligence, electrical engineering rules, automatic terminal numbering, and hardware configuration export.

How do I calculate 24V DC power supply requirements for a DCS cabinet?

Use the TIA Selection Tool or EPLAN to aggregate module backplane current demands, sensor loop transmitter loads (typically 25 mA per 4-20 mA loop), actuator inrush currents, and apply a 20-30% spare capacity safety margin.